iSi Protection Lens Cap for V5/V5 Pro attaches to the 82mm adaptor ring and protects the front of the lens and V5 C-PL including the NEW Enhanced Landscape C-PL. If you are walking from a location to another and you dont want to remove the CPL and the 82mm adaptor ring, the NiSi Protection Lens Cap for V5/V5 Pro is what you need to be sure that everything is well protected and mounted on the lens ready for the next shot. The lens cap also allows you to leave the 82mm adaptor ring attached to the lens when you pack it away in your bag.